Increase precision and max value of bone matrix floats

- I just made up a technique that is probably 30% efficient, this is
  something to revisit in the future

armature.glsl

@@ -24,17 +24,6 @@ float decode_normalized_float32(vec4 v)
 	return sign * (v.z*255.0 + v.y);
 }
 
-// in textures, color elements are delivered as unsigend normalize floats
-// in [0, 1]. This makes them into [-1, 1] as the bone matrices require 
-// such values to be correct
-vec4 make_signed_again(vec4 v) {
-	v.x = 2.0 * v.x - 1.0;
-	v.y = 2.0 * v.y - 1.0;
-	v.z = 2.0 * v.z - 1.0;
-	v.w = 2.0 * v.w - 1.0;
-	return v;
-}
-
 void main() {
 	vec4 total_position = vec4(0.0f);
 
@@ -46,17 +35,15 @@ void main() {
 
 		float y_coord = (0.5 + index)/bones_tex_size.y;
 
-		vec4 col0 = texture(bones_tex, vec2((0.5 + 0)/bones_tex_size.x, y_coord));
+		mat4 bone_mat;
-		vec4 col1 = texture(bones_tex, vec2((0.5 + 1)/bones_tex_size.x, y_coord));
-		vec4 col2 = texture(bones_tex, vec2((0.5 + 2)/bones_tex_size.x, y_coord));
-		vec4 col3 = texture(bones_tex, vec2((0.5 + 3)/bones_tex_size.x, y_coord));
 
-		col0 = make_signed_again(col0);
+		for(int row = 0; row < 4; row++)
-		col1 = make_signed_again(col1);
+		{
-		col2 = make_signed_again(col2);
+			for(int col = 0; col < 4; col++)
-		col3 = make_signed_again(col3);
+			{
-
+				bone_mat[col][row] = decode_normalized_float32(texture(bones_tex, vec2((0.5 + col*4 + row)/bones_tex_size.x, y_coord)));
-		mat4 bone_mat = mat4(col0, col1, col2, col3);
+			}
+		}
 
 		vec4 local_position = bone_mat * vec4(pos_in, 1.0f);
 		total_position += local_position * weight;

main.c

@@ -1083,7 +1083,7 @@ Armature load_armature(MD_Arena *arena, MD_String8 binary_file, MD_String8 armat
 			.label = (const char*)nullterm(arena, MD_S8Fmt(arena, "%.*s-vertices", MD_S8VArg(armature_name))).str,
 			});
 
-	to_return.bones_texture_width = 4;
+	to_return.bones_texture_width = 16;
 	to_return.bones_texture_height = (int)to_return.bones_length;
 
 	Log("Amrature %.*s has bones texture size (%d, %d)\n", MD_S8VArg(armature_name), to_return.bones_texture_width, to_return.bones_texture_height);
@@ -2726,7 +2726,9 @@ PixelData encode_normalized_float32(float to_encode)
 	assert(to_return_vector.z < 255.0f);
 	to_return_vector.z /= 255.0f;
 
-	// w is unused for now
+	// w is unused for now, but is 1.0f (and is the alpha channel in Vec4) so that it displays properly as a texture
+	to_return_vector.w = 1.0f;
+
 
 	PixelData to_return = {0};
 
@@ -2739,6 +2741,21 @@ PixelData encode_normalized_float32(float to_encode)
 	return to_return;
 }
 
+float decode_normalized_float32(PixelData encoded)
+{
+	Vec4 v = {0};
+	for(int i = 0; i < 4; i++)
+	{
+		v.Elements[i] = (float)encoded.rgba[i] / 255.0f;
+	}
+
+	float sign = 2.0f * v.x - 1.0f;
+
+	float to_return = sign * (v.z*255.0f + v.y);
+
+	return to_return;
+}
+
 
 void draw_armature(Mat4 view, Mat4 projection, Transform t, Armature *armature, float elapsed_time)
 {
@@ -2772,28 +2789,19 @@ void draw_armature(Mat4 view, Mat4 projection, Transform t, Armature *armature,
 		for(int col = 0; col < 4; col++)
 		{
 			Vec4 to_upload = final.Columns[col];
-			assert(-1.1f <= to_upload.x && to_upload.x <= 1.1f);
-			assert(-1.1f <= to_upload.y && to_upload.y <= 1.1f);
-			assert(-1.1f <= to_upload.z && to_upload.z <= 1.1f);
-			assert(-1.1f <= to_upload.w && to_upload.w <= 1.1f);
-
-			// make them normalized
-			to_upload.x = to_upload.x/2.0f + 0.5f;
-			to_upload.y = to_upload.y/2.0f + 0.5f;
-			to_upload.z = to_upload.z/2.0f + 0.5f;
-			to_upload.w = to_upload.w/2.0f + 0.5f;
-
-			to_upload.x = clamp01(to_upload.x);
-			to_upload.y = clamp01(to_upload.y);
-			to_upload.z = clamp01(to_upload.z);
-			to_upload.w = clamp01(to_upload.w);
 
 			int bytes_per_pixel = 4;
-			int bytes_per_row = bytes_per_pixel * 4;
+			int bytes_per_column_of_mat = bytes_per_pixel * 4;
-			bones_tex[bytes_per_pixel*col + bytes_per_row*i + 0] = (MD_u8)(to_upload.x * 255.0);
+			int bytes_per_row = bytes_per_pixel * armature->bones_texture_width;
-			bones_tex[bytes_per_pixel*col + bytes_per_row*i + 1] = (MD_u8)(to_upload.y * 255.0);
+			for(int elem = 0; elem < 4; elem++)
-			bones_tex[bytes_per_pixel*col + bytes_per_row*i + 2] = (MD_u8)(to_upload.z * 255.0);
+			{
-			bones_tex[bytes_per_pixel*col + bytes_per_row*i + 3] = (MD_u8)(to_upload.w * 255.0);
+				float after_decoding = decode_normalized_float32(encode_normalized_float32(to_upload.Elements[elem]));
+				assert(fabsf(after_decoding - to_upload.Elements[elem]) < 0.01f);
+			}
+			memcpy(&bones_tex[bytes_per_column_of_mat*col + bytes_per_row*i + bytes_per_pixel*0], encode_normalized_float32(to_upload.Elements[0]).rgba, bytes_per_pixel);
+			memcpy(&bones_tex[bytes_per_column_of_mat*col + bytes_per_row*i + bytes_per_pixel*1], encode_normalized_float32(to_upload.Elements[1]).rgba, bytes_per_pixel);
+			memcpy(&bones_tex[bytes_per_column_of_mat*col + bytes_per_row*i + bytes_per_pixel*2], encode_normalized_float32(to_upload.Elements[2]).rgba, bytes_per_pixel);
+			memcpy(&bones_tex[bytes_per_column_of_mat*col + bytes_per_row*i + bytes_per_pixel*3], encode_normalized_float32(to_upload.Elements[3]).rgba, bytes_per_pixel);
 		}
 	}
 	sg_update_image(armature->bones_texture, &(sg_image_data){
@@ -2991,6 +2999,22 @@ void do_serialization_tests()
 
 	MD_ReleaseScratch(scratch);
 }
+
+void do_float_encoding_tests()
+{
+	float to_test[] = {
+		7.5f,
+		-2.12f,
+		100.2f,
+		-5.35f,
+	};
+	ARR_ITER(float, to_test)
+	{
+		PixelData encoded = encode_normalized_float32(*it);
+		float decoded = decode_normalized_float32(encoded);
+		assert(fabsf(decoded - *it) < 0.01f);
+	}
+}
 #endif
 
 Armature armature = {0};
@@ -3064,6 +3088,7 @@ void init(void)
 	do_metadesk_tests();
 	do_parsing_tests();
 	do_serialization_tests();
+	do_float_encoding_tests();
 #endif
 
 #ifdef WEB